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ryzh [129]
3 years ago
10

A spectrophotometer measures the transmittance or the absorbance, or both, of a particular wavelength of light after it has pass

ed through a liquid sample. Before the transmittance or absorbance of the sample is measured, a cuvette filled only with solvent, called the blank, is placed in the spectrophotometer and measured. Select the reason that, after the blank is measured, the cuvette must be placed in the spectrophotometer in the same orientation each time that it is used. O The spectrophotometer will break if the cuvette position is changed during the experiment. O The transmittance of the liquid must be measured in the same place each time. O The cuvette will only fit into the spectrophotometer in one orientation. O The transmittance of the cuvette must be measured in the same place each time.

Chemistry
1 answer:
lutik1710 [3]3 years ago
5 0

Answer:

The cuvette will only fit into the spectrophotometer in one orientation.

Explanation:

There is an arrow always marked on the cuvette that indicates how to place it inside the spectrophotometer. The sides of the cuvette also have small edges that if light passes through them, spurious light can be detected due to poor positioning. The spurious light does not get through the entire sample, if we want to measure the absorbance. With a cuvette in the indicated position, the procedure is measured and its reference value is taken, and then compared with other cuvettes to be used.

Look the picture!

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Which of the following hydrocarbons has a double bond in its carbon skeleton?1) C3H82) C2H63) CH44) C2H45) C2H2
Kipish [7]

Answer:

  • <u>C₂H₄</u>  (option number 4)

Explanation:

A hydrocarbon with a <em>double bond</em> in its carbon skeleton is an alkene and has the general form:

  • C_nH_{2n}.

This is, the number of hydrogen atoms is twice the number of carbon atoms.

On the other hand, alkanes have only single bonds, and the compounds with a triple bond in its carbon skeleton are alkynes.

Review each choice:

1) <u>C₃H₈:</u>

  • In this case, the number of hydrogen atoms is 2×3 + 2 = 6 + 2 = 8, which is corresponds to an alkane, not an alkene.

2)<u> C₂H₆</u>

  • For this, the number of hydrogen atoms is 2 × 2 + 2 = 4 + 2 = 6. Again an alkane, not alkene.

3) <u>CH₄</u>

  • Hydrogen atoms: 1 × 2 + 2 = 4 ⇒ an alkane

4) <u>C₂H₄ </u>

  • Hydrogen atoms: 2 × 2  = 4.  This is precisely the relation for an alkene, so this is the hydrocarbon that has a double bond in its carbon skeleton.

  • The chemical formula may be writen as CH₂ = CH₂, to show the double bond.

So, this is the correct answer.

5) <u>C₂H₂</u>

  • Hydrogen atoms: 2 × 2 - 2 = 4 - 2 = 2. This relation of carbon and hydrogen atoms corresponds to a compound with triple bond, i.e an alkyne: CH≡CH.
8 0
3 years ago
The internal energy of a system is always increased by ________. A. adding heat to the system B. adding heat to the system and h
lord [1]

Answer:

B. adding heat to the system and having the system do work on the surroundings

Explanation:

The internal energy of a system is the energy contained within the system. From first law of thermodynamics we have the equation : dq=du+dw

and we know that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another therefore du is zero. dq = dw this means that the entire heat supplied is converted into work (on the surroundings)

However, some of the heat supplied is also used to increase the internal energy of the system

3 0
3 years ago
Read 2 more answers
Beta particles will: 1. bend toward the North Pole of a magnet. 2 bend toward the South Pole of the magnet 3 not be affected by
Setler79 [48]
Beta particles will bend toward the South Pole of the magnet.

Hope this helped!
8 0
3 years ago
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PLS ANSWER FAST AHAH<br><br> distilled water is a pure substance <br> true or false ?
mr Goodwill [35]

Answer:

True

Explanation:

If you see distilled water, it's a pure substance. That means that there are only water molecules in the liquid. A mixture would be a glass of water with other things dissolved inside, like one of those powders you take if you get sick or Kool-Aid.

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3 years ago
Luis is helping his parents paint a border around the walls of a room. He uses a stencil to repeat the same design on each wall
iren [92.7K]

Answer:

Polymerization.

Explanation:

Polymerization can be defined as a type of chemical reaction in which molecules that are relatively small in size chemically combine to form a huge chain of molecules.

Simply stated, polymerization refers to a chemical reaction where two or more smaller molecules react to produce larger molecules of the same network or repetitive structural units.

In polymerization, the relatively small molecules are generally referred to as monomers while the larger molecules they produce are known as polymers.

Polymerization is given by the chemical formula;

nA -----> A(n).

In this scenario, Luis uses a stencil to repeat the same design on each wall to form one long grapevine with a bunch of grapes every foot along its length.

Hence, the type of chemical reaction this best model is polymerization because it involved repeating the same design (monomers) to form a long grapevine with a bunch of grapes (polymers).

5 0
3 years ago
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